Factitious host species impact on the outcome of multiparasitism between egg parasitoids

Trichogramma parasitoids are biological control agents of a large number of lepidopterous pests. Mass production of these Trichogramma parasitoids is carried out on different factitious host eggs where the cost for mass rearing is high and the production efficiency is low. Therefore, efficient means and techniques for mass production of these parasitoids are needed. Host eggs of Chinese oak silkworm, Antheraea pernyi, not only proved effective for the mass production of a single Trichogramma species but also showed great potential for simultaneously producing two different Trichogramma species through multiparasitism. Here, we evaluated the outcomes of multiparasitism between Trichogramma chilonis and T. leucaniae reared on the eggs of two factitious hosts, Antheraea pernyi and Corcyra cephalonica. Our study indicated that parental wasps of both Trichogramma species reared on A. pernyi performed outstandingly in all aspects of multiparasitism on A. pernyi eggs. In contrast, significantly low parasitism rates for parental wasps reared on C. cephalonica and subsequently low emergence rates for their offspring were recorded for multiparasitism on A. pernyi eggs. Parental wasps reared on different host eggs significantly affected the emerged offspring numbers for both Trichogramma species per A. pernyi egg. Significantly high numbers of offspring for specific species of Trichogramma emerged per A. pernyi egg when the parental wasps of that species were reared on A. pernyi eggs compared to the other species reared on C. cephalonica eggs. The present study concluded that rearing host species had a great impact on the performance of parental wasps in the multiparasitism of Trichogramma parasitoids on A. pernyi eggs and clearly confirmed that T. chilonis and T. leucaniae parasitoids can be massively produced on A. pernyi eggs through multiparasitism. Our results provide useful information about rearing hosts, which could provide two different Trichogramma species in the field at a time for the suppression of pest populations.